Amplifying system



Oct. 14, 1930. F. c. BARTON 1,778,058

AMPLIFYING SYSTEM Filed Nov. 14, 1925 Fig. 1.

l. l a) 2.; 2w m1 J Frederick C. Barton.

as Aohorney.

Patented Oct. 14, 1930' UNITEDVSTATES PATENT OFFICE 'rnnnnnrox o. BARTON, or soHnNncTAnY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIC COMPANY, A CORPORATION on NEW YORK AMPLIFYING SYSTEM Application filed November 14, 1925 Serial No. 69,201.

invention relates to apparatus for amplifying voltage impulsesand applying them to a sound reproducing device such as a loud speaker, and has for its principal object the provision of an-improved amplifying system that may be operated by alternating current supplied from a house lighting circuit or the like.

control and cathode heating circuits of the amplifiers andto the exciting winding of the reproducingdevice where such a winding is'utilized. In orderto simplify the control of such systems it is desirable that these potentials be applied through a single source and that the connections to this source be completed onlywhenthe voltage applied to the amplifier terminals is maintained within predetermined limits. In accordance with my invention, these results are accomplished byimpedance means adapted to be connected to the sourcein a manner to produce the h required potentials and by a voltage regulating device comprising means for controlling the connections of the source to amplifying apparatus.

My invention will be better understood from the following description when con- SlClQI'GCl; in connection with the accompanyingrdrawings andits scope will be pointed [out in the appended claims. I v

I Referring tothe drawings, Fig. 1 shows an i amplifying apparatus whereinmy invention has been embodied; and Fig. 2 is a perspective view of the. device utilized to regulate the plate voltage of the amplifiers.

Fig; 1 shows a transformer 1 comprising a ;primary winding 2- adapted to be connected toasuitable source through contacts 3 and 4 and leads 5 and 6, a secondarywinding 7 for transmitting'current to amplifying tubes 8 and 9 and to the fieldwinding 10 of a sound reproducingdevice 11, a secondary winding 1.12 for supplying heating current to the cathodes'of thermionic rectifiers13 and 14 50 through whichcurrent is supplied to the sistors 23 and 24, and the field winding 10 is connected between the cathode 19 and anode 25 of tube 8 through the primary circuit 26 of a transformer 27. A condenser 28 connected in shunt to the resistor 22 is provided forshunting high frequency currents past the resistor. Contacts 29 and 30 are provided for connecting a voltage regulating device to the load or anode circuit of the tube 8. It will be observed that the tube 9 is provided with a grid 31 which is connected to the cathode 16 through the secondary circuit 32 of transformer 27 and a negative bias resistor 33 shunted by a condenser 34 and with an anode 35 which is connected to the cathode 16 through windings 10 and 12, rectifiers 13 and 1a, winding 7, resistors 20, 23 and 33 and winding 15. Smoothing means shown as condensers 36 and 37 are connected in shunt to the field winding 10.

As indicated by Fig. 2 a glow tube or other suitable vol regulating means is provided with contacts 21) and 30 for connecting the electrodes and 4:0 througn contacts 29 and 30 to the terminals of res s or and with short circuited contacts 3 and a for completing the primary circuit of the t sfornier 1 through a ballast lamp it will be apparent that this arrai ment of contacts has the advantage that i is impossible to energizethe am lifying apparatus without at the same time ail'on'ling it protection against excessive voltage. it will be observed also that the contacts 3 and 30 are made somewhat larger than the contacts 4- and 29 so that incorrect insertion of the glow tube in the receptacle is impossible.

It should be noted that heating current is supplied to the cathode 19 from the main secondary circuit 7 of the transformer 1, the magnitude of this current being dependent on the potential drop'produced in resistor 23 by current supplied to the exciting winding 10. This current is substantially constant due to the smoothing eiiect oi condensers 36 and 37 and the exciting winding 10 which acts f as a smoothing inductance.

The reproducing device 11 also comprises an operating coil 41 that is interposed between the poles 4 2 and 13 of a core member tl and is connected to the anode or load circuit of tube 9 through a transformer 46. The

sound reproducing device 11 is of the type wherein a diaphragin is operated by means of the operating 0011 all which is located in the strong magnetic field produced by the field coil 10. For convenience of illustration the diaphragm and other details of the device have been omitted.

a The operation of the apparatus will be readily understood it it be assumed that the voltage regulating device 38 is placed in the socket comprising contacts 3, 4, 29 and 130.

-Und'er these conditions current rectified by the devices 18 and 1 1 1s supplied to the field w nding 10 through resistors 23, 22, 2 1 and 20, the potential drop of resistorQS is applied to the cathode 19 oi tube 8, the potential drop of resistor 22 is applied to the anode or load circuit of tube 8, the combined potential drops of resistors 22 and 24 are applied device.

to the anode circuit of tube 9, and the nega tive biases of the grids of tubes '8 and 9 are determined by resistors 20and 33 respectively.

Variation in the current transmitted through the tube 8 is determined by the voltage impulses applied to the grid 18 through leads 17 and these variations in current produced in the anode circuit of tube 8 are uti-.'

lized to vary the control potential and load current or tube 9 through which the voltage impulses are amplified and applied to the operating coil 41 of the sound reproducing It will thus be observed that all the potent als required for operation otthe apparatus are applied through a single source and that this source cannot be connected to the apparatus unless it is protected from ex cessive voltage.

The embodiment of the nvention illustrated and described herein has been selected for the purpose of clearly setting forth the principles involved. It will be apparent, however, that the invention is susceptible of Y being modified to meet the different conditions encountered in its use and I therefore aim to cover by the appended claims allmodt fioations within the true spirit and scope oi my invention.

What I claim as newand desire to secure by Letters Patent of the United States is 1. The combination of a sound producing heating current through the cathode of the first named amplifier.

2. The combination of a sound producing device including a winding, a thermionic amplifier comprising a grid'tor controlling the transmission of current between its cathode and anode, means connected between said cathode and anode for transmitting voltage impulses to said winding, voltage regulating means adapted to be connected between said cathode and anode, current-supply means, and means operable to prevent the connection of said current supply means to said amplifier before said regulating means is connected thereto. 7 r i r V i i 3. The combination of a sound producing device including a winding, a thermionic amplifier including a grid interposed between a cathode and anode, means connected between said cathode and grid fortransmitting voltage impulses to said grid, a source of current,

impedance means connected to said source in series with said winding for diverting heating current through said cathode and for diverting current through a circuit comprising said cathode and anode, and means connected between said-cathode and; anode for supplying impulses to said windin 1. The combination of a sound producing device including field and operating windings, a thermionic amplifierincluding a grid 1 interposed between a cathode and anode,

means connected between said cathode and grid for transmitting voltage impulses to said grid, a source of current, impedance means connected to said source in series with said field winding for diverting heating current through said cathode and for. diverting current through said anode andcathode, and means connected between said cathode and anode for supplying impulses to said operating winding.

5. The combination of a sound reproducing device comprising a winding, a thermionic amplifier conprising a grid" for controlling the transmission of current through its output circuit, means for transmitting voltage'impulses to said grid, means'comprising a transformer, a rectifier andan impedance device connectedm said output clrcuit, voltage regulating means adapted to be'conne'cted to said impedance device for regulating the voltage applied to said output circuit through said transformer and rectifier, and means opergrid for controlling the transmission of cur-V able to prevent closure of the primary circuit of said transformer until said regulating means is connected to said impedance device.

6. The combination ofa sound producing device comprising a Winding, a plurality of thermionic amplifiers each provided With'a rent between its cathode and anode, means for transmitting voltage impulses to the grid of one of said amplifiers, means interconnecting thecathode and anode of said amplifier for applying amplified impulses to the grid of another of said amplifiers, means comprising alternating current supply means and a rectifier connected between the cathode and anode of said second mentioned amplifier for applying amplified impulses to said winding, means for transmitting rectified current from said current supply means for heating the cathode of said first mentioned amplifier, and

means for transmitting alternating current from said current supply means for heating the cathode of said second mentioned amplifier.

In Witness whereof I have hereunto set my hand this 13th day of November, 1925.

FREDERICK C. BARTON. 

